Communications is an integral piece of a line differential relay, as the currents from one line terminal must be sent to relays at other line terminals to perform the differential calculation. This requires the use of a digital communications
channel, which is commonly a multiplexed channel where channel switching may occur. The analog information must be precisely Phase Selector21P21GTrip OutputResetDir. Supv.Open PolInit BFARV, I Open Pole(s)Open PoleDetector
1.Single pole trip logic.9 Transmission Line Protection Principlestime synchronized between the line ends for the differential alculation to be correct